Winshield wiper, especially for motor vehicles and method for production of said windshield wiper

ABSTRACT

A windshield wiper system, and a method for producing such a system, in particular for a motor vehicle, having at least one wiper bearing ( 14 ) substantially comprising an injection-moldable material, in particular plastic, in which a wiper shaft ( 16 ) is supported at least in such a way that it can swing back and forth, and in the region of the wiper shaft ( 16 ), the wiper bearing ( 14 ) has a substantially hollow-cylindrical segment ( 24 ) on whose inner surface ( 34 ) at least one groove ( 40 ) is provided; at least one, in particular riblike, accumulation of material ( 38 ) is provided on the outer surfaces of the hollow-cylindrical segment ( 24 ), which accumulation is disposed in the radially outward direction of the groove ( 40 ) relative to the axis of rotation of the wiper shaft ( 16 ).

PRIOR ART

[0001] The invention relates to a windshield wiper system and a methodfor producing such a system as generically defined by the preambles tothe independent claims. Numerous windshield wiper systems are alreadyknown which have a basic structure assembled from tubes, also known as atubular mounting, on each of whose ends a wiper bearing is secured.These wiper bearings each have a wiper shaft, on the end of which awiper arm that supports a wiper blade is secured.

[0002] Increasingly, to reduce weight, the wiper bearings are being madefrom plastic; a bearing plate is omitted, and the wiper shaft issupported directly in the plastic. Stringent demands are made of thewiper bearing in terms of wear, since these wiper bearings must functionproperly over many thousand wiping cycles. To that end, these wiperbearings must be lubricated, and defined grooves must be provided forthe lubricant.

ADVANTAGES OF THE INVENTION

[0003] The windshield wiper system of the invention, having thecharacteristics of the main claim, has the advantage that the wiperbearing can be produced of plastic by injection molding, and therequisite groove for receiving the lubricant can be produced using acircular-cylindrical tool die. This reduces tool costs, since no furthermachining steps are needed to create a lubrication groove. Moreover, thewiper shaft can be dimensioned with a smaller diameter, since no notchesfor creating a grease chamber are needed in the wiper shaft.

[0004] By the provisions recited in the dependent claims, advantageousrefinements of and improvements to the characteristics recited in themain claim are obtained.

[0005] It is especially advantageous if a plurality of grooves, inparticular three to four of them, for receiving a lubricant areprovided, since in this way an adequate quantity of lubricant can beplaced in the bearing, without impairing the overall stability of thebearing.

[0006] It is also advantageous if the accumulation of material isembodied as substantially block-shaped.

[0007] Block-shaped accumulations of material in the casting mold can beproduced without problems, without significantly increasing tool costs.This is equally true for essentially semicylindrical accumulations ofmaterial.

[0008] It is also considered advantageous if the accumulation ofmaterial is disposed substantially parallel to the wiper shaft. In thisarrangement, the lubricant can easily be placed in the groove.

[0009] It is especially advantageous, however, if the accumulation ofmaterial is disposed substantially helically, since then the bearingsurface is uninterrupted in one or more specified force directions.Hence in operation, that is, when the bearing shaft is rotating andalternating changes in load direction are occurring, the portions of theinner surface of the wiper bearing on the shaft always haveapproximately the same area. This prevents any alternation betweenlinear contact and area contact.

[0010] It is especially advantageous if the grooves have a minimumspacing from the bottom and top faces of the wiper bearing, andparticularly if this spacing is about 10 mm. The result is strongsealing of the bearing, so that the lubricant cannot be washed out.Moreover, this provides a complete cylindrically radial bearing face inthe region of the bottom and top faces of the wiper bearing, whichimproves the running properties of the wiper bearing.

[0011] Since the width of the groove can be adjusted via the width ofthe accumulation of material, it furthermore proves advantageous if theaccumulation of material is disposed substantially flatly. In this way,large quantities of lubricant can be placed in the bearing region.

[0012] The method of the invention defined by the characteristics ofclaim 9 has the advantage that without further processing steps, groovesfor receiving a lubricant are created on the inner surface of the wiperbearing, on the slide face between the wiper bearing and the wipershaft. This is possible because a simple cylindrical tool die is used;by this method, arbitrary chamber geometries can be produced. Inparticular, helical chambers can be created in this way, despite arectilinear tool opening.

[0013] Moreover, by this method the groove can be embodied entirely onthe inside, so that lubricant placed in the wiper bearing before thewiper shaft is inserted cannot escape or be washed out.

DRAWINGS

[0014] Exemplary embodiments of the invention are shown in the drawingsand described in further detail in the ensuing description. Shown are:

[0015]FIG. 1, a windshield wiper system of the invention shownschematically.

[0016]FIG. 2, a wiper bearing of the invention, in perspective;

[0017]FIGS. 3a, 3 b and 3 c, various sections through thehollow-cylindrical segment of the wiper bearing;

[0018]FIG. 4a, a wiper bearing with helical grooves, in perspective;

[0019]FIG. 4b, a wiper bearing with helical grooves, in a perspectivesectional view.

[0020]FIG. 5, longitudinal sections through wiper bearings with variousgrooves.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0021] In FIG. 1, a windshield wiper system 10 is shown schematically.It substantially comprises a tubular mounting 12, which carries a wiperbearing 14 on one end. A wiper shaft 16 is supported in this wiperbearing and is connected on one end to a wiper arm 18 in a manner fixedagainst relative rotation. On the other side, the wiper shaft 16 isconnected to a pivot crank 20 in a manner fixed against relativerotation; this crank is driven by a wiper motor 22, via a rod linkagenot shown for the sake of simplicity.

[0022]FIG. 2 shows a wiper bearing 14 of a windshield wiper system 10 ofthe invention in a perspective view. This wiper bearing 14 substantiallycomprises a hollow-cylindrical segment 24, in which the wiper shaft 16can be supported. Transversely to the wiper shaft, fastening regions 26a, 26 b are formed on; they serve to secure the wiper bearing 14 to thetubular mounting 12 on the one hand and to the vehicle body on theother. To improve the stability of the connection between thehollow-cylindrical segment 24 and the fastening regions 26 a, 26 b, thelatter are secured to the segment 24 by means of fastening ribs 28.Moreover, the hollow-cylindrical segment 24 has a bottom face 30 and atop face 32, which limit it in its length. Both on the bottom face 30and the top face 31, the segment 24 furthermore has a respectivereinforcing ring 31 a, b, which may also be embodied integrally with thesegment 24.

[0023] The slide face between the wiper shaft 16 and thehollow-cylindrical segment 24 is created by an inner surface 34 of thehollow-cylindrical segment 24. On an outer surface 36 of thehollow-cylindrical segment 24 that describes a cylindrical jacket,riblike accumulations of material 38 are disposed, extending axiallyalong the hollow-cylindrical segment 24. However, these accumulations ofmaterial 38 are guided along the bottom and top faces 30, 32 of thehollow-cylindrical segment 24 only down as far as a minimum spacing a.

[0024] In FIGS. 3a, 3 b and 3 c, cross sections through thehollow-cylindrical segment 24 of the wiper bearing 14 are shown. FIG. 3ashows a bottom face 30 of the segment 24, and FIG. 3c shows the top face32 of the segment 24, respectively just above and just below thereinforcing rings 31 a and 31 b. In FIG. 3b, a cross section is shownthrough the middle—in the axial direction—between the bottom face 30 andthe top face 32. The fastening regions 26 (FIG. 2) and the reinforcingrings 31 a, 31 b are left out here, for the sake of simplicity.

[0025] In FIG. 3b, four accumulations of material 38 can be seen,distributed uniformly over the outer surface 36 of the segment 24. Onegroove 40 is disposed on each corresponding inner surface 34 of thecylindrical segment 24. This groove 40 is created by because when theplastic cools in the casting process, increased shrinkage occurs becauseof the accumulations of material 38, creating sunken places. Theaccumulations of material 38 are purposefully embodied such that thesunken places form the grooves 40, which can serve to receive alubricant for the wiper bearing 14. The accumulations of material 38 areat least as thick as the wall thickness of the hollow-cylindricalsegment 24, for the sake of achieving an adequate depth of the grooves40.

[0026] In FIGS. 3a and 3 c, that is, in the regions of the bottom andtop faces 30, 32, no accumulations of material 38 are embodied on theouter surface 36, and therefore no grooves 40 have been created in theseregions. The result is ideal sealing of the wiper bearings 14.

[0027] In FIG. 4a, as in FIG. 2, a wiper bearing 14 is shown inperspective. Here, however, the accumulations of material 38 aredisposed helically on the outer surface 36 of the cylindrical segment24. The two fastening regions 26 a and 26 b are clearly visible here aswell. One fastening region 26 a is embodied cylindrically. It is thrustinto the tubular mounting 12 of the windshield wiper system 10 andlocked, for instance by crimping. The other fastening region 26 b isembodied as an eyelet 42, which is surrounded by a collar 44. Thiscollar serves to secure the windshield wiper system 10 to the body of avehicle. In FIG. 4b, a longitudinal section through a wiper bearing 14of FIG. 4a is shown. The inner surface 34 of the hollow-cylindricalsegment 24 is clearly visible here. It—in a way corresponding to theaccumulations of material 38 of FIG. 4a—has the helical groove 40, whichserves to receive a lubricant.

[0028] In FIGS. 5a, 5 b and 5 c, various longitudinal sections are shownthrough various cylindrical segments 24 of a windshield wiper system 10of the invention. In FIG. 5a, the grooves 40 are shown, which extendparallel to the axis of rotation of the wiper shaft. They are eachspaced apart by a minimum spacing A from the bottom and top faces 30, 32of the cylindrical segment 24, to assure adequate tightness of thebearing. In FIG. 5b, the grooves 40 are embodied as very wide, so thatthe groove 40 is more like a two-dimensional region. In FIG. 5c, thegroove 40 is disposed helically.

[0029] In a refinement, it is also possible to make bores in theaccumulations of material 38, through which bores the lubricant can beintroduced later, for instance during maintenance. To increase thestability, it is also conceivable to embody the reinforcing rings 31 a,b of metal, and to form the rest of the wiper bearing onto the rings.The accumulations of material 38 can also comprise a different materialfrom the rest of the bearing components. In that case, however, thevarious materials must be injection-molded in rapid succession.

[0030] In principle, the method can be performed, or the wiper bearing14 embodied, with other materials than plastic instead.

1. A windshield wiper system, in particular for a motor vehicle, havingat least one wiper bearing (14) substantially comprising aninjection-moldable material, in particular plastic, in which a wipershaft (16) is supported at least in such a way that it can swing backand forth, and in the region of the wiper shaft (16), the wiper bearing(14) has a substantially hollow-cylindrical segment (24) on whose innersurface (34) at least one groove (40) is provided, characterized in thatat least one, in particular riblike, accumulation of material (38) isprovided on the outer surfaces of the hollow-cylindrical segment (24),which accumulation is disposed in the radially outward direction of thegroove (40) relative to the axis of rotation of the wiper shaft (16). 2.The system of one of the foregoing claims, characterized in that aplurality of grooves (40), in particular from three to four of them andpreferably four of them, are provided for receiving a lubricant.
 3. Thesystem of claim 1 or 2, characterized in that the accumulation ofmaterial (38) is embodied as substantially block-shaped.
 4. The systemof one of claims 1-3, characterized in that the accumulation of material(38) is embodied substantially semicylindrically.
 5. The system of oneof the foregoing claims, characterized in that the accumulation ofmaterial (38) is disposed substantially parallel to the wiper shaft(16).
 6. The system of one of claims 1-4, characterized in that theaccumulation of material (38) is disposed substantially helically. 7.The system of one of claims 1-5, characterized in that the accumulationof material (38) is disposed substantially flatly.
 8. The system of oneof the foregoing claims, characterized in that the at least one groove(40) has a minimum spacing (a) in particular of 5 mm to 15 mm,preferably 10 mm, from the bottom and top faces (30, 32) of thehollow-cylindrical segment (24).
 9. A method for producing a windshieldwiper system, in particular a windshield wiper system of one of theforegoing claims, having at least one wiper bearing (14), which forsupporting a wiper shaft (16) has a substantially hollow-cylindricalsegment (24), characterized in that by targeted accumulation of material(38) at the outer surfaces of the hollow-cylindrical segment (24), atleast one groove (40) is created on the slide face between the wiperbearing (14) and the wiper shaft (16) by means of shrinkage of material.